Fw: [sdiy] ETI vocoder input amps

[Hallvard Tangeraas]

At 15:20 +0200  26.10.01, jhaible at t-online.de wrote:


>> It's been a while, but I believe I looked over the circuit schematics
>> and noticed these errors as well, but also saw that the PCB itself
>was
>> OK.

>I have *not* checked the layout, but:
>
>>  http://home.c2i.net/w-392864/vocoder/amp_schematic.gif (schematic)
>
>*This* drawing has the errors, and the handwritten pin numbers at
>IC1b *confirm* the error there.
 [..........]

I've looked through the circuit again and again, but I still can't find
out what's wrong. With my limited electronics knowledge I have however
figured out what you explained as being the errors in the schematics
and fixed them.
The PCB itself however looks OK, so why it doesn't work is beyond me,
especially when Magnus Danielson has one of these which does indeed
work.

I can see how hard it is to check out the PCB layout, so I enlarged it
and have drawn the components again as well as marking them. As I said
it looks OK to me.
Here's the PCB layout (with components):

http://home.c2i.net/w-392864/vocoder/new_revised/pcb_overview.gif

I haven't drawn in the where the jack connectors connect (I have drawn
where on the PCB they connect, but not where these points correspond to
on the jacks as I've tried several connections and none of them worked).


....and here's the schematic which should be OK now:

http://home.c2i.net/w-392864/vocoder/new_revised/corrected_amp_schematic.gif



Hallvard
-- 
Notator/Creator SL : <http://www.notator.org>
Atari Launchpad    : <http://launchpad.atari.org>